44 THAUMANTIAS OCTONA. 



3. Thaumantias aronautica, Forbes. 

 Plate IX, Fig. 3. 



The umbrella of this minute species, which is still smaller than T. quadrata, is oblong, 

 and becomes elongated during contraction. It is smooth, transparent, and colourless. The 

 margin bears four fine, colourless, filiform tentacula, which are often extended to a prodigious 

 length, as compared with the dimensions of the body, or with the small size, both of length 

 and diameter, into which they can contract themselves. When magnified, they exhibit a 

 moniliform appearance. They spring from four large bulbs of a pale yellow colour, with traces 

 of an interior vesicle, but no brightly coloured ocelli. In the interspaces of the margin are 

 yellow tubercles, three between each pair of tentacles, the central one largest, but all very 

 small as compared with the tentacle-bulbs. Down the sub-umbrella, which is of an oblong 

 form, and sometimes, when vigorously contracting, of a pear-shape, run the four gastric vessels, 

 traversing at exactly half its height as many very small ovate reproductive glands, of a pale 

 yellow colour. The stomach is sessile ; when contracted, shortly campanulate ; when ex- 

 tended, long and quadrangular, reaching nearly to a level with the ovaries. The mouth is 

 surrounded by four simple lanceolate lips. 



Small as this pretty creature is, it is evidently adult, and presents its permanent characters. 

 When confined in a glass tube, filled with salt water, it resembles a miniature balloon moored 

 by five silken cables. I met with it in localities far apart, viz. off Brassay, and in Hamna Voe, 

 in Papa, both in the Zetland seas, in July 1845 ; and during the following month in the Sound 

 of Skye, among the Hebrides. All the specimens were alike. I judged it to be adult, from 

 the defined and firm condition of the reproductive glands, and the microscopic structure of 

 the tentacles and their bulbs. 



Plate X, f. 3, a, represents it of the size of nature ; 3, h, magnified, with the tentacles 

 extended ; 3, c, seen from above, with the tentacles contracted ; 3, d, the stomach extended ; 

 and 3, e, contracted ; ^,f, one of the reproductive glands. 



** Marginal tentacles, eight. 



4. Thaumantias octona^ Forbes. 

 Plate VIII, Fig. 4. 



The umbrella of this small and peculiar species, is only about two tenths of an inch in 

 height, globose, or sub-orbicular, smooth, and transparent. The margin presents the peculiar 

 feature of bearing eight exactly similar pinkish tentacles, springing from conspicuous, bright 

 yellow, bulbous bases, each bearing a defined red ocellus. In the marginal spaces, between 

 each pair of tentacles, are two colourless tubercles placed close together. These do not 

 appear ever to give rise to tentacula. The sub-umbrella is short compared with the umbrella, 

 and is hemispherical. In the course of the four vessels, which run to join the marginal 

 vessel opposite to the origins of four of the tentacles, are four small yellow or tawny ovate 

 ovaries, placed on the lower half of the sub-umbrella. The stomach is very small in proportion 

 to the size of the animal, rather elongated, and quadrangular in shape, of a yellowish or fawn 

 colour, with four minute black dots at its base. The four lips are short, acute, and triangular. 



